I hope your eye heals on its own - I have had sudden vision issues in the past, and they sometimes improve spontaneously. Here is a little info about NAION:
https://www.brighamandwomens.org/neurology/neuro-ophthalmology/non-arteritic-anterior-ischemic-optic-neuropathy
Here is a discussion on Mayo Connect by some people who have experienced it. https://connect.mayoclinic.org/discussion/non-arteritic-ischemic-optic-neuropathy/
Also, on a more positive note, I have a hole in my ??? just outside my central vision - diagnosed 15 years ago - while it did not go away, my brain was able to compensate. Now I only notice it under very low light or stressful conditions. The ophthalmologist checks it 2 times a year, and it never seems to change.
Sue